Saturday, February 28, 2015

Blooms - Blades - Historic Realities

I don't often make references over to Facebook.
The main reason why is that I actually find the format itself unwieldy and not at all suitable for any kind of serious discussion. (This not helped by the fact that Facebook increasingly will only function correctly with high speed connections and the latest software - and I have neither).

There is however, currently a very interesting discussion going on about 'what they knew' - in reference to bloomery iron smelting, modifying carbon contents and tool making. 
My own comments (below) come in something like 35th in the stream. There is some pretty good stuff there (even if in shorter bites), so go take a look if you can...
Hi, there's something I've been wondering.
Most Scandinavian literature debates why there's a tradition for laminated blades here. The conclusion is always part because steel was expensive.
At the same time the local archaeological consensus is that Scandinavians were unable to make steel other than by carburizing in a box up until quite recently (when crucible steel came), and that making steel in a bloom furnace is impossible.
Of course as Mark Green and others have shown, ...and I've tried myself, it is quite easy to carburize in a hearth.
So why should it be expensive? Could it be because while the low C outer layer could be rougher and less worked/refined, they insisted on heavily refined steel for the edge?
(my additions)
Hinted at by Tim Young and Lee Sauder : We do need to remember that in the distant past there was no 'scientific' understanding of process, no open sharing of information, extremely limited transportation. An individual was very much fixed to his local 'tradition' of working, only had locally available materials. Those of us who have experimented with differing furnace types and radically different ores (even different charcoals) know that there is a dance between furnace, ore, air and fuel. For those of us who first started the present 'Early Iron' movement, believe me, there were a huge number of complete failures before any kind of iron at all was ever produced. If we had kept working in isolation, with only our local resources, I dare say we would still be just making slag!
My first smelt attempt - L'Anse aux Meadows, 2001 (everything we did was WRONG!)

The objective of an ancient iron master was to make as much *usable* working bar as possible with the least amount of effort (labour, time, materials). The blacksmtith (much less the bladesmiith) was a totally separate profession. My understanding is that although higher carbon blooms might sometimes be produced, this was likely more on a firing by firing rate. It may be that one individual iron master in a certain spot might be more dependably able to make a specific quality of iron than others around. This could be the result of knowledge / experience / materials - or any combination of these factors (maybe even just dumb luck!).
Replica Currency Bars - for Parks Canada, 2001

I find there is often confusion between theoretical archaeologists and practical experimenters. Just because something can be demonstrated experimentally it is *possible* does not mean it was *common* (I think most of the experimenters here have produced cast iron by accident more than once for example!). On the reverse, all that can ever be said is our modern experiments only prove "A" way - we can never be certain we are demonstrating "The" way... 
Iron Smelt as Historic Re-creation - Vinland 2010

Saturday, February 21, 2015

Bladesmithing Interview - Part 2

3.Have you used smelted bog iron to make knives or swords? How do they perform?

I have made a number of small knives as replicas of known Viking Age types, plus some modern designed knives utilizing bloom iron as one component (Hector's Bane the best example there).
For my own work, I am concentrating on re-discovering lost historic smelting methods, which is certainly different than using the processes to produce the best possible blade making materials. This is an important distinction.

Historically, the aim of the smelt master was not to produce blade materials, but instead to get the largest bloom of iron that could be easily forged for general purpose work. Our modern understanding of how carbon (or other elements) can modify the base iron for ideal cutting edges just did not exist. Even in the Japanese tradition, there was no clear knowledge of how modifying a furnace or changing aspects of the firing might produce a specific result. Instead, the blade maker would use experience to selectively pick pieces with hoped for characteristics out of a larger pile of random quality bloom fragments (based on colour, crystal structure, fracture lines). Here I am talking about Northern European, Early Medieval, methods, also with the initial reduction of ore to bloom (not secondary modifications like 'hearth steel' or wootz).
So the most common base material past on from the smelt master into the hands of the Viking Age blacksmith was simple bloomery iron, compressed to working bars. This material would have next to no carbon content, and would contain varying amounts of slag tendrils (even inside the same source bar). As each bloom itself varies in its carbon from top to bottom, most certainly accumulated experience would teach some parts / methods of working resulted in blades with slightly better edge holding than others. There would certainly be no kind of predictabililty of results as is enjoyed by modern bladesmiths, working with our standardized industrial metal stocks.
'Bloom Seax' - Simple Norse era natural branch handle

What this means is that historic blades of bloom iron (or accurately created replicas) are simply not hard - and they just do not hold an edge. So much so that one of the most common personal objects for a Norse or Saxon male was a small sharpening stone, worn attached to the belt. Straight bloomery iron blades require almost constant sharpening! You also see this in the artifact knives, with most blades well worn down from all the sharpening during their use life.

For the modern designs, I use the bloom iron specifically to highlight its unique texture. Blades like Hector's Bane have bloom iron exterior slabs forge welded to a carbon steel core. As with other inset cutting edge styled blades, it is this modern alloy core that is forming the actual cutting edge. So the bloom iron is not really a functional component, but a decorative one.

'Hector's Bane'

Honestly, given the high skill and massive labour needed to create bloomery iron in the first place, this material is just to valuable in my eyes to waste. So I have never undertaken a series of destructive tests to firmly determine the absolute compairison properties of bloomery iron. Given the wide variation between individual blooms, I'm not even sure how useful any comparision to modern alloy steels would even be.

Tuesday, February 17, 2015

Beads = Female ???

Posted by Jeroen on the Bladesmith's Forum:
A rare view of a burial including a longsax (or transitional), with scabbard fittings in situ: http://benedante.blo...r-grave-at.html

Longsax scabbard remains are pretty rare (I only know of one other example on top of my head), so this is is a great find! Hopefully there will be some cleaned photos of the scabbard mounts. Also interesting to see is the sword, which apparently had a fully organic hilt. Another interesting thing are the beads. I'd expect beads in a female grave, so is this a female warrior or just a man wearing a necklace? The dating they gave is too early, and should be around 700AD.
"Frankish warrior's grave of c. 600 CE uncovered during excavations for the TGV train tracks in Alsace"

 It was pointed out in a comment by Scott :
... from the comments at the bottom of the link it looks like there was a mistake in how the pictures were assembled.  The beads are apparently from a different grave.
"Collar or necklace of glass beads."

 First point might be that the source is from the internet, and further from an individual's personal blog. So the images might have come from anywhere, and the descriptive text is quite limited (!!)

The concept of beads = female is very much a 'Victorian' frame of reference. In the past graves were sex determined with a simple weapon = male / bead = female method. As archaeologists have (finally) gotten a bit more careful, this (largely male) point of view has been questioned.
The majority of at least Viking Age Scandinavian graves (the only cultural set I can speak too with any real knowledge) that contain beads have very few individual beads. Something like 3 - 5 as an average. Bearing in mind that every grave find with a full string can really throw that average, its just more typical that any grave many only have one or two beads found. This really means you have to question using beads as a sex determiner.
The position of an beads, and more importantly the possible inclusion of broaches is actually more significant. Beads found in what suggests a line across the chest are likely to have been supported between broaches - a use pattern that is certainly female use. A bead string (or a couple of beads) found around the neck can not realistically be used in isolation to determine sex of the individual.
There are some graves that from the bone evidence are females, but also contain weapons.
Of interest here would also be some graves from Finland that have larger knives with elaborate sheet or cast metal scabbard covers, the blades mounted to run in line with the belt. (Luistari #56, Eura, Satakunta, Finland)
Image scanned from 'Vikings - North Atlantic Saga' pg 111
 I know the thrust a the Bladesmith's Forum is an examination of the weapons in detail. But I do think it helps to have a larger picture of how weapons as objects were markers of social status especially. A sword included with a body might be telling a far more complex story that might be perceived at first glance...

I would most certainly refer readers to Neil Peterson's extensive research and data collection on the topic of glass beads in the Viking Age posted over on the DARC web site - HERE.

Saturday, February 14, 2015

Bloomery Iron for Bladesmithing - some Questions and Answers (A)

Some Background:

I was contacted a couple of weeks back by a staff writer from a major magazine that focuses on contemporary bladesmithing:

I'm working on a story about knifemakers who have smelted their own bog iron. I was perusing the Bladesmith's Forum when I came across a post you wrote in January 2014 describing your experience with smelting. Would you be interested in talking to me for the story? I'm curious to learn more about the process of turning raw bog iron into blade and about the history of how smiths in the Iron Age worked with their material. 
There was a bit of back and forth. I was careful to explain that although I do consider my knowledge and experience with especially Northern European Early Medieval (Viking Age) furnaces to be considerable, my focus has been on the 'ore to bloom' phase, certainly not on the 'bar to blade' part. I suggested some further background reading off the (massive) documentation on my web site -  Experimental Iron Smelting. 

This lead to a list of specific questions.
Like usual, I started off like some absent minded college professor, pretty much delivering a compressed lecture on experimental archaeology, Viking Age history, the theory of direct process bloomery iron furnaces...
'This is just taking so long' says I. 
'Maybe you should not be trying to be so much the teacher' says she.
The guy wanted an *interview* - not a college level course...

But since I've written the stuff anyway, and knowing full well the final article is unlikely to do more than give me a line or two, I'm putting up the full 'answers' here...

2 (*). I'm interested in your historical reenacting. What is it like to smelt under historical conditions? 
Reconstructed Viking Age smelt at Vinland (L'Anse aux Meadows NHSC, 2010)

Leaving aside the larger questions of experimental archaeology and whether modern people can ever really duplicate the past (**).

The single biggest change I find in working in a 'historic' environment is the absence of modern time keeping. As early 21st Century North Americans, so much of our lives are controlled by our (obsessive?) use of time measuring devices. In iron smelting, reproducible and predictable results are framed in terms of burn rates, which are standard volumes against time.
My own team has used a number of 'ancient' type ways to determine time. When working with a hand powered bellows, using your heart rate is one possible measure. One of the team studies early music, and he wrote a couple of songs / chants to use to help regulate bellows stroke rates. Both of these methods were used in the final 'all Viking Age' iron smelt demonstration / experiment we undertook in 2010 at L'Anse aux Meadows NHSC for Parks Canada. We did have an observer / recorder keeping measured experimental data, but did not consult those notes until after the smelt was over.

My standard principle is 'History stops when Safety starts'. 

You notice in the image from the Vinland experiment that although the team members are in Viking Age clothing and using historic type tools, we are still wearing modern safety glasses. Going blind from having a hot piece of slag or scale damage an eye is also historically accurate - but we are not completely crazy. Use of leather aprons and gloves has been standard for metalworkers since ancient times, if only to protect clothing, which was considerably more valuable before modern industrial textiles. Wool and Linen fabrics are actually considerably more functional around the furnace than modern synthetic materials. The main safety concern I have had over wearing historic clothing is in the footwear. Soft soled Viking Age shoes can be very slippery, and certainly provide little protection if you drop something on your foot!

In operating a 'short shaft' direct process bloomery furnace, higher air volumes have proven to produce larger, more dense iron blooms. In fact, blooms most like those few found in the archaeology. You most certainly will get iron with less air, but those blooms tend to be smaller (less efficient) and much more lacy in composition.
There remains an open question on just what kind of bellows was actually used for iron smelting in the Early Medieval period, as there is nothing remaining in terms of archaeological evidence. The size of the reconstructed bellows created for the Vinland experimental series was largely guess work, but the measurements were based on the theoretical requirements for air inside the furnace used.
The effective pumping rate was one stroke per second, alternating between the two chambers. Individuals varied on their stroke force (delivery pressure), but averaged 60 - 75 strokes per minute. This without interruption, over the course of the entire firing sequence extending roughly 5 hours. We found that to maintain the needed consistency, we needed four individuals, working in roughly 10 minute shifts. This labour force needed to be at least semi-skilled to this task. This is a requirement totally separate to the needs of feeding and operating the furnace itself.
Its easy to see why the development of water powered bellows, starting in the 700's and moving across Europe through to about 1100 AD, had such a huge impact on bloomery iron production.
Of course there is also the labour involved in preparing all the required raw materials. Hundreds of pounds of charcoal (wood gathered, cut, baked, broken). Ore to be found, dug, roasted, broken. Clay to be dug, dried, screened, re-mixed. A furnace to be built.
All this just gives you a raw bloom. This still needs to be refined by hammering, folding, re-welding into a working bar. Its only at that point the bladesmith can start working his own art.

* Question 1 was related to contributing some images for the final article. I will be adding some of the ones I suggested as illustrations through my own series here.

** This is where I realized I was going out of control!
I had written the following as a mere lead in to what is above for question 2:

One of the huge problems in attempting to discover possible historic / ancient physical practise is the whole concept of 'can modern people really duplicate the mind set of historic people'. This actually is a topic of considerable debate in the museum and archaeology field.
Coupled with that is the whole problem of attempting to re-discover what at base is a completely 'lost' working tradition. Outside of Japan, there is no living progression of these skills down into the modern day. This is especially true for Northern Europe, where archaeological evidence is extremely limited, and the technology itself had shifted before any written descriptions of the original processes had been recorded.
Leaving that mainly aside, there are a couple of primary problems that impact any attempt to reproduce historic iron smelting methods:

- Outside of some very rare and isolated examples, there are almost no working traditions of smelting iron that extend down into the modern age. Japan is the primary exception to this. However, because ore type directly influences furnace design and operation, Japanese methods are quite different to those undertaken in Northern Europe. This is important, because most North Americans are patterning their furnaces around what are essentially late Iron Age / Early Medieval European 'short shaft' type furnaces. There are a number of modern makers specifically basing their work on Japanese models (Jesus Herandez would be one). Lee Sauder started with African prototypes, which he moved away from as he developed the base level understanding of the smelting process. (It was from this work and him that almost everyone else in NA learned the basics by the way.) Lee has recently returned to work on these systems.

- Not only is European process not represented as a surviving tradition, the exact type of small scale direct process bloomery that most of us are using today was mostly abandoned as a working technology by the middle of the Medieval period. The specific technology of processing raw ore into working metal bars has changed several times over the last 1000 years, which earlier methods replaced with newer systems that offered larger scale production, better efficiency and increased control of the results. The big shift from wrought iron to mild steel via the Bessemer process in the later 1850's being an example modern blacksmiths (should be) familiar with.
This is not quite a direct severing of ancient / historic process. Sometimes shifting realities will re-introduce an older working method. One of the best examples is the rapid growth of small to medium scale iron smelting in America just post revolution. Cut off from British industrial supply, the new nation had to rapidly and massively increase its production volume. Typical 'Yankie Ingenuity' was combined with abundant wood resources for charcoal,  particularly in the New England region with its many locations for water power, resulting in many smaller scale bloomery furnace operations springing up.

February 15 - May 15, 2012 : Supported by a Crafts Projects - Creation and Development Grant

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